Figure 1. Experimental realization of a ring-lattice potential with an adjustable weak link (red arrow).

Measured intensity distribution with an azimuthal lattice spacing of 28 μm and a ring radius of 88 μm (see Methods section). The centre peak is the residual zero-order diffraction. The effective dynamics of a condensate in such a system is governed by the qubit potential as discussed in Eq.(2). The size of the structure is scalable and a lower limit is imposed by the diffraction limit of the focusing optics (see Methods section). Several rings can be arranged in a stack, along the propagation axis of the laser beam (shown in Fig. 5).